Head mounted displays (“HMDs”) enable a user to interactively immerse oneself in a virtual reality environment to experience that environment remotely. HMDs allow a user to experience the environment by allowing the user to turn the user's head wherein a corresponding point of view displayed to the user on the HMD changes based on the direction of the user's head. Early versions of HMDs suffered from high latency between the time that head movement is detected and when the point of view is changed, due to hardware limitations. The result of this high latency was induced nausea in the user, likely caused by a conflict in the user's vestibular senses in relation to movement displayed to the user's eyes. The clinical name for this form of nausea is Video Game Motion Sickness (VGMS), and is commonplace when first person point of view action video games are played near a large screen display. VGMS is further magnified by use of an immersive display such as HMDs, particularly if the motion and verstibular feedback experienced by a user are not synchronized.
Recent hardware advances have significantly reduced latency between user head movement input detected by an HMD and changes in the field of view displayed to the user on the HMD. This has significantly reduced the inducement of nausea in a user when the user is at a stationary location in the virtual reality environment and simply viewing surroundings of the user in the virtual reality environment such as an interior of buildings or vehicles.
While advances in hardware have reduced the inducement of nausea in a user when the user is stationary relative to a surrounding virtual reality environment, attempts to navigate the user through the virtual reality environment have been found to rapidly induce nausea in the user by creating a conflict between a user's vestibular sense and virtual reality image viewed by the user. This is particularly true in “near field” virtual reality environments, wherein a user is in close proximity to objects within the virtual reality environment.
Various forms of input controls exist that allow a user to navigate a virtual environment that attempt to reduce any motion sickness related to virtual reality navigation. For example, U.S. Pat. No. 6,135,928 provides a large sphere for a user to walk on, wherein movement of the sphere is translated into motion through a virtual reality environment. Similarly, U.S. Pat. No. 7,780,573 describes a treadmill type apparatus for translating movement of a user in a virtual reality environment in multiple planes, and U.S. Pat. No. 5,902,214 describes a set of mechanical stirrups for detecting user movement and translating the detected movement into movement in a virtual reality environment. While these devices attempt to solve issues related to movement through a virtual reality environment, these and other similar devices are substantially complicated and large because they are configured to detect a user's body motion and translate that motion into movement in the virtual reality environment.
In other instances, users are allowed to freely navigate a virtual reality environment using one or more joysticks or similar controllers, wherein there is no connection between directional movement and a user's view on the virtual reality headset. This type of navigation frequently induces nausea in the user due to perceived motion conflict between the user's optical and vestibular systems.
Other attempts have been made to allow a user to interact with a virtual reality environment. For example, U.S. Pat. Nos. 6,127,990 and 6,359,603 describe a system for allowing a user to view a portion of a large display by moving the user's head. However, these systems do not provide for navigation of a user through a virtual reality environment, but instead are limited to viewing a display.
What is needed, therefore, is a system and method for navigating an immersive virtual reality environment that minimizes effects of motion sickness on a user by restricting movement of the user based on an orientation of a head mounted display worn by the user.